"I would first determine how much time is needed to complete the deliverables. Then, I will assess the skill set needed to complete these deliverables, and if possible break the tasks down so I can delegate accordingly to team members who are trained or skilled. If needed, I'll reach out to other personnel who aren't necessarily part of the project team but are available. If that's not an option, then I could request to outsource the work to a contractor.
If all these steps take too long that it's impossible to deliver by launch, I'll run an impact assessment with a new estimated timeline. Then, I'll present this plan to the stakeholders and project sponsors immediately. My main concern at this point would be to keep everyone aware of the contingency plan and re-align their expectations with the new timeline."